| Symbol | Greek Symbol | Definition | US | Metric | Value |
|---|
| \(Da\) |
- |
Damkohler number |
dimensionless |
dimensionless |
- |
| \(\delta\), \(\;\lambda\) |
delta , lambda |
dampening coefficient |
- |
- |
- |
| \(\zeta\) |
zeta |
damping ratio |
dimensionless |
dimensionless |
- |
| \(f\), \(\;C_f\), \(\;f_d\) |
- |
Darcy friction factor |
dimensionless |
dimensionless |
- |
| \(Da\) |
- |
Darcy's law |
- |
- |
- |
| \(Da\) |
- |
Darcy number |
dimensionless |
dimensionless |
- |
| \(DW\) |
- |
Darcy-Weisbach equation |
dimensionless |
dimensionless |
- |
| \(D\) |
- |
Dean number |
dimensionless |
dimensionless |
- |
| \(De\) |
- |
Deborah number |
dimensionless |
dimensionless |
- |
| \(w_d\) |
- |
Debye angular frequency |
- |
- |
- |
| \(q_d\) |
- |
Debye angular wave number |
- |
- |
- |
| \(\lambda_d\) |
lambda |
Debye length |
- |
- |
- |
| \(\Theta_d\) |
Theta |
Debye temperature |
- |
- |
- |
| \(D\) |
- |
Debye-Waller factor |
- |
- |
- |
| \(\lambda\) |
lambda |
decay constant |
- |
- |
- |
| \(d\) |
- |
deceleration |
\(ft\;/\;sec^2\) |
\(m\;/\;s^2\) |
- |
| \(dB\) |
- |
decibel |
dimensionless |
dimensionless |
- |
| \(d\), \(\; \delta\) |
delta |
deflection |
- |
- |
- |
| \(\delta\) |
delta |
deformation |
\(in \;or\; ft\) |
\(mm \;or\; m\) |
- |
| \(x\) |
- |
degree of ionization |
- |
- |
- |
| \(\mu\), \(\;S\) |
mu |
degree of saturation |
- |
- |
- |
| \(F\) |
- |
degrees of freedom |
- |
- |
- |
| \(\rho\) |
rho |
density |
\(lb\;/\;ft^3\) |
\(kg\;/\;m^3\) |
- |
| \(\rho_a\) |
rho |
density of air |
- |
- |
- |
| \(\rho\) |
rho |
density (aether) |
constant |
constant |
\(9.605125782\;x\;10^{24}\;kg\;/\;m^3\) |
| \(\rho_f\) |
rho |
density of fluid |
\(lb\;/\;ft^3\) |
\(kg\;/\;m^3\) |
- |
| \(\rho_o\) |
rho |
density of object |
\(lb\;/\;ft^3\) |
\(kg\;/\;m^3\) |
- |
| \(\rho_v\) |
rho |
density of vapor |
\(lb\;/\;ft^3\) |
\(kg\;/\;m^3\) |
- |
| \(\rho\) |
rho |
density of an ideal gas |
\(lb\;/\;ft^3\) |
\(kg\;/\;m^3\) |
- |
| \(N_e\), \(\;\rho\) |
rho |
density of state |
- |
- |
- |
| \(\rho_w\) |
rho |
density of water |
- |
- |
- |
| \(z\) |
- |
depth |
\(in \;or\; ft\) |
\(mm \;or\; m\) |
- |
| \(\partial\) |
partial |
derivative (rate of change) |
- |
- |
- |
| \(R^2\) |
- |
determination coefficient |
dimensionless |
dimensionless |
- |
| \(T_d\) |
- |
dewpoint temperature |
\(^\circ F\) |
\(C\) |
|
| \(d\) |
- |
diameter |
\(in \;or\; ft\) |
\(mm \;or\; m\) |
- |
| \(\epsilon\) |
epsilon |
dielectric constant |
- |
\(F\;/\;m\) |
- |
| \(P\) |
- |
dielectric polarization |
- |
- |
- |
| \(d\), \(\;\Delta\) |
delta |
differential |
- |
- |
- |
| \(D\), \(\;D_n\), \(\;D_p\) |
- |
diffusion coefficient |
\(lbf\) |
\(N\) |
- |
| \(L_n\), \(\;L_p\) |
- |
diffusion length |
- |
- |
- |
| \(\alpha\) |
alpha |
diffusivity |
\(ft^2\;/\;hr\) |
\(m^2\;/\;s\) |
- |
| \(a\), \(\;b\) |
- |
dimension |
\(in \;or\; ft\) |
\(mm \;or\; m\) |
- |
| \(DA\) |
- |
dimensional analysis |
- |
- |
- |
| \(k_d\) |
- |
dimensional constant |
- |
- |
- |
| \(n\) |
- |
dimensionless exponent |
- |
- |
- |
| \(K\) |
- |
dimensionless factor |
- |
- |
- |
| \(N\), \(DN\) |
- |
dimensionless number |
- |
- |
- |
| \(\mu\), \(\;C_d\) |
mu |
discharge coefficient |
dimensionless |
dimensionless |
- |
| \(d\), \(\;\vec{d}\), \(\;s\), \(\;\delta\) |
delta |
displacement |
\(in \;or\; ft\) |
\(mm \;or\; m\) |
- |
| \( \vec{D}\) |
- |
displacement current |
- |
- |
- |
| \(\psi\), \(\;\delta\) |
psi, delta |
dissipation factor |
- |
- |
- |
| \(E_d\) |
- |
dissociation energy |
- |
- |
- |
| \(d\), \(\;l\), \(\;x\), \(\;y\) |
- |
distance |
\(in \;or\; ft\) |
\(mm \;or\; m\) |
- |
| \(s\) |
- |
distance along cable |
\(in \;or\; ft\) |
\(mm \;or\; m\) |
- |
| \(a\) |
- |
distance to lowest cable point |
\(in \;or\; ft\) |
\(mm \;or\; m\) |
- |
| \(w\) |
- |
distributed load |
\(lbf \;/\; ft\) |
\(N \;/\; m\) |
- |
| \(E_d\) |
- |
donor ionization energy |
- |
- |
- |
| \(K_2\) |
- |
downstream resistance coefficient |
dimensionless |
dimensionless |
- |
| \(D\) |
- |
draft |
\(in-wg\) |
kPa |
- |
| \(C_d\) |
- |
drag coefficient |
dimensionless |
dimensionless |
- |
| \(F_d\) |
- |
drag force |
\(lbf\) |
\(N\) |
- |
| \(v_{dr}\) |
- |
drift velocity |
- |
- |
- |
| \(\zeta\) |
zeta |
dryness fraction |
- |
- |
- |
| \(\rho_{db}\) |
rho |
dry bulk denssity of soil |
\(lb/gal\) |
\(g/mL\) |
- |
| \(Du\) |
- |
Dukhin number |
dimensionless |
dimensionless |
- |
| \(Q\), \(\;q\) |
- |
dynamic pressure |
\(lb\;/\;in^2 \;or\; psi\) |
\(Pa\) |
- |
| \(a\) |
- |
dynamic speed constant |
\(ft \;/\; min\) |
- |
- |
| \(\mu\), \(\;\eta\) |
mu (used in mechanical), eta (used in chemical) |
dynamic viscosity |
\(ft-lbf\;/\;ft^2-sec\) |
\(mPa-s\) |
- |
| \(\mu_w\) |
mu |
dynamic viscosity of water |
\(ft-lbf\;/\;ft^2-sec\) |
\(mPa-s\) |
- |
| Symbol |
Greek Symbol |
Definition |
US |
Metric |
Value |
